, said to live under bridges
. Depending on who you ask, they may be miners
, they may turn to stone
in the sun
, or whatever suits your fancy
for your particular piece of fictive fantasy
Also a name for a Internet user who asks stupid questions with the sole intention of getting a major response. For example, the 12-year-old AOL user who goes into alt.rape.surviors and posts a message with the words "Suck my dick, and get back in the kitchen and make me some pie!" is most assuredly a troll.
It is best if you not repond to them. If you are lucky, they'll turn to stone when the sun comes up.
Note the analogy with Trolling in the fishing sense. You stick a tasty morsel on a hook, and drag it through a population hoping someone will bite. For all our sakes, be smarter than a fish.